Evaporator and vehicle provided with refrigeration cycle having the same

ABSTRACT

The invention provides an evaporator ( 1 ) having a front heat exchange assembly ( 1 A) and a rear heat exchange assembly ( 1 B) arranged at an air inlet side and an air outlet side, respectively, and adjacent to each other, each of the heat exchange assemblies ( 1 A), ( 1 B) comprising a pair of upper and lower headers ( 2 ), and a multiplicity of refrigerant channels ( 3 ) each having an upper and at lower end connected to the upper header and lower headers. The upper and lower headers ( 2 ) of the rear heat exchange assembly ( 1 B) are internally provided with vertical partitions ( 21 )for internally dividing the headers ( 2 ) into portions arranged laterally so as to reverse the direction of upward or rearward flow of a refrigerant through the refrigerant channels of the rear heat exchange assembly ( 1 B) every specified number of refrigerant channels and thereby provide at least one group ( 3 U) of upward refrigerant channels in each of the left half and the right half of the real heat exchange assembly ( 1 B). When the evaporator ( 1 ) is used in a motor vehicle air conditioner, the portions of air passing through the let and right halves of the evaporator ( 1 ) become uniform in temperature, obviating the likelihood of giving discomfort to the riders, even when the clutch of the compressor is disengaged because the upward refrigerant channel group ( 3 U) wherein the refrigerant is stagnates in a large amount is positioned at each of the left and right sides of the rear heat exchange assembly ( 1 B).

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is an application filed under 35 U.S.C. §111(a)claiming the benefit pursuant to 35 U.S.C. §119(e)(1) of the filing dateof Provisional Application No. 60/330,682 filed Oct. 29, 2001 pursuantto 35 U.S.C. §111(b).

TECHNICAL FIELD

[0002] The present invention relates to evaporators and vehiclesprovided with a refrigeration cycle such as a motor vehicle airconditioner having the evaporator.

[0003] The “front”and “rear” of the evaporator are based in the flow ofair; the term “front” refers to the side of the evaporator where airenters, and the term “rear” to the side thereof from which the air flowsout. The terms “left” and “right” refer respectively to the left andright sides of the evaporator as it is seen from the front rearward.

BACKGROUND ART

[0004] In the case of motor vehicle air conditioners, the air cooled bythe evaporator is forced out of a plurality of air vents into theinterior of the vehicle. Usually for introduction into the interior ofthe vehicle, the portion of air passing through the left half of theevaporator flows out of the vent at the left (e.g. as opposed to thedriver's seat), and the portion of air passing through the right half ofthe evaporator flows out of the vent at the right (e.g. as opposed tothe passenger seat). Accordingly, if there is a temperature differencebetween the former portion of air and the latter portion of air, theriders are likely to feel discomfort. This problem becomes morepronounced since there is in recent years a tendency for the distancebetween the evaporator and the air vent to become smaller. The airtemperature difference appears markedly with an increase in the lateraldimension of the evaporator.

[0005] To enable the left and right halves of the evaporator to provideair of uniform temperature, various refrigerant flow patterns haveheretofore been contrived for use in evaporators. FIG. 13 shows anexample of pattern. The illustrated evaporator 500 comprises a frontheat exchange assembly 500A and a rear heat exchange assembly 500B whichare adjacent to each other. Each of the heat exchange assemblies 500A,500B comprises a pair of upper and lower horizontal headers 502extending laterally, and a multiplicity of vertical refrigerant channels503 arranged laterally at a spacing and each having an upper endconnected to the upper header 502 and a lower end connected to the lowerheader 502. A refrigerant inlet 504 is provided at the left end of theupper header 502 of the rear heat exchange assembly 500B, and arefrigerant outlet 505 is provided at the left end of the upper header502 of the front heat exchange assembly 500A. The upper headers 502 ofthe front and rear heat exchange assemblies 500A, 500B communicate witheach other through communication tube portions 506 at portions thereoftoward their right ends. The upper header 502 of the rear heat exchangeassembly 500B is internally divided into two left and right portions bya vertical partition 502A so that the refrigerant flows downward throughthe channels 503 of the left half of the rear heat exchange assembly500B, with the refrigerant flowing upward through the channels 503 ofthe right half of the rear heat exchange assembly 500B.

[0006] The upper header 502 of the front heat exchange assembly 500A isinternally divided into two left and right portions by a verticalpartition 502A so that the refrigerant flows downward through thechannels 503 of the right half of the front heat exchange assembly 500A,with the refrigerant flowing upward through the channels 503 of he lefthalf of the front heat exchange assembly 500A.

[0007] With the evaporator 500 of FIG. 13, the left half of the rearheat exchange assembly 500B wherein the refrigerant temperature islowest, and the left half of the front heat exchange assembly 500Awherein the refrigerant temperature is highest are adjacent to eachother along the direction of flow of air. Further the right half of therear heat exchange assembly 500B wherein the refrigerant temperature issecond lowest, and the right half of the front heat exchange assembly500A wherein the refrigerant temperature is second highest are adjacentto each other along the direction of flow of air. Consequently, theportions of air A passing through the left and right halves respectivelybecome substantially uniform in temperature.

[0008] With the evaporator 500 described, however, the portions of air Apassing through the respective left and right halves of the evaporator500 fail to become uniform in temperature to produce a temperaturedifference between the air portions forced out of the left and rightvents respectively, when the clutch mechanism of the compressor isautomatically disengaged, namely, when the flow of refrigerant throughthe evaporator 500 is temporarily halted, in order to preventovercooling of air.

[0009] An object of the present invention is to provide an evaporator,for example, for use in motor vehicle air conditioners which providesair of uniform temperature as passed through the left and right halvesthereof even when the clutch mechanism of the compressor is disengagedand which is therefore free of the likelihood of giving discomfort tothe riders.

DISCLOSURE OF THE INVENTION

[0010] When the clutch mechanism of the compressor is coupled to thecrankshaft of the engine while a motor vehicle air conditioner is inoperation, it is thought that the refrigerant flows through therefrigerant channels of the evaporator, as uniformly vaporized dependingon the extent of evaporation of the refrigerant in the channels. Whenthe clutch mechanism of the compressor is disengaged, on the other hand,the supply of refrigerant to the evaporator is temporarily interrupted,and the refrigerant remaining in the evaporator appears to exhibit thefollowing behavior. The portion of refrigerant remaining in the group ofdownward refrigerant channels tends to flow into the subsequent group ofupward refrigerant channels, partly under the action of gravity. On theother hand, the portion of refrigerant remaining in the group of upwardrefrigerant channels is returned even if acting to flow upward againstthe gravity and is therefore liable to stagnate in this group ofchannels. For this reason, it is thought that a larger amount ofrefrigerant is stagnant in the upward refrigerant channel group than inthe downward refrigerant channel group.

[0011] Accordingly, the present inventor has found that the followingrefrigerant flow patterns are useful for evaporators to fulfill theforegoing object.

[0012] Thus, the present invention provides an evaporator having a frontheat exchange assembly and a rear heat exchange assembly arranged at anair inlet side and an air outlet side, respectively, and adjacent toeach other, each of the heat exchange assemblies comprising a pair ofupper and lower headers extending laterally, and a multiplicity ofrefrigerant channels arranged laterally at a spacing and each having anupper end connected to the upper header and a lower end connected to thelower header, a refrigerant inlet being provided at one end of the upperor lower header of the rear heat exchange assembly, a refrigerant outletbeing provided at one end of the upper or lower header of the front heatexchange assembly, the upper or lower header of the rear heat exchangeassembly communicating at a portion thereof toward the other end withthe upper or lower header of the front heat exchange assembly at aportion thereof toward the other end by communication means, the upperand lower headers of the rear heat exchange assembly being internallyprovided with vertical partitions for internally dividing the headersinto portions arranged laterally so as to reverse the direction ofupward or rearward flow of a refrigerant through the refrigerantchannels of the rear heat exchange assembly for every specified numberof refrigerant channels and thereby provide at least one group of upwardrefrigerant channels in each of a left half and a right half of the rearheat exchange assembly.

[0013] While the clutch mechanism of the compressor is disengaged, arelatively large amount of refrigerant is stagnant in the group ofupward refrigerant channels in each of the left and right halves of therear heat exchange assembly of the evaporator described, so that theportions of air passing through the respective left and right halves ofthe evaporator are maintained at an approximately uniform temperature.

[0014] With the evaporator of the invention, it is desired that therefrigerant channels of the rear heat exchange assembly adjacent to therefrigerant channels of the front heat exchange assembly wherein therefrigerant is in an superheated state be included in the group ofupward refrigerant channels.

[0015] The refrigerant channels of the front heat exchange assemblywherein the refrigerant is in an superheated state have a relativelyhigh temperature of course when the compressor clutch mechanism isengaged and also when the clutch mechanism is disengaged, whereas if atleast some of the upward refrigerant channels of the rear heat exchangeassembly wherein the refrigerant portion of relatively low temperatureis stagnant are arranged adjacent to the above front assembly channels,the air passing through the left and right halves of the evaporator canbe maintained at a more uniform temperature.

[0016] With the evaporator of the invention, the refrigerant to becaused to flow into the group of upward refrigerant channels of the rearheat exchange assembly which are positioned remotest from therefrigerant inlet may be made to dividedly flow into and flow upwardthrough a plurality of refrigerant channels of the front heat exchangeassembly which are adjacent to the plurality of refrigerant channels ofthe rear heat exchange assembly constituting the group, by causing thelower headers of the front and rear heat exchange assemblies tocommunicate with each other by flow-dividing communication means at theheader portions corresponding to the plurality of refrigerant channels.

[0017] Similarly the evaporator may be so adapted that the refrigerantto be caused to flow into the group of downward refrigerant channels ofthe rear heat exchange assembly which are positioned remotest from therefrigerant inlet is made to dividedly flow into and downward through aplurality of refrigerant channels of the front heat exchange assemblywhich are adjacent to the plurality of refrigerant channels of the rearheat exchange assembly constituting the group, by causing the upperheaders of the front and rear heat exchange assemblies to communicatewith each other through flow-dividing communication means at the headerportions corresponding to the plurality of refrigerant channels.

[0018] When the refrigerant to be caused to flow into the group ofupward or downward refrigerant channels of the rear heat exchangeassembly which are positioned remotest from the refrigerant inlet iscaused by flow-dividing communication means to dividedly flow into aplurality of refrigerant channels of the front heat exchange assemblywhich are adjacent to rear assembly channels of the group, the pressureloss of the refrigerant can be diminished.

[0019] The rear assembly channels of upward or downward refrigerantchannel group positioned remotest from the refrigerant inlet can be madeindependent of the front assembly channels adjacent to the rear assemblychannels. Alternatively, the former channels may each be united with thecorresponding one of the latter channels. In the latter case, therefrigerant can be caused to flow from the rear heat exchange assemblyto the turn portion of the front assembly substantially over the entirewidth of the evaporator, whereby the pressure loss of the refrigerantcan further be reduced.

[0020] With the evaporator of the invention, the refrigerant inlet isprovided at one end of the lower header of the rear heat exchangeassembly, and the rear heat exchange assembly has the group of upwardrefrigerant channels as each of the first and the third groups ascounted from the refrigerant inlet side, and a group of downwardrefrigerant channels as each of the second and fourth groups as countedfrom the inlet side.

[0021] In this case, at least some of the upward refrigerant channels inthe first group of the rear heat exchange assembly are usually arrangedadjacent to the front assembly refrigerant channels wherein therefrigerant is in the superheated state. Further in this case, it isusually desirable to use at least seventeen refrigerant channels foreach of the front and rear assemblies from the viewpoint of reducing thepressure loss of the refrigerant.

[0022] The evaporator of the invention may be so designed that therefrigerant inlet is provided at one end of the upper header of the rearheat exchange assembly, and that the rear heat exchange assembly has thegroup of upward refrigerant channels as each of the second and thefourth groups as counted from the refrigerant inlet side, and a group ofdownward refrigerant channels as each of the first and third groups ascounted from the inlet side.

[0023] In this case, at least some of the upward refrigerant channels inthe second group of the rear heat exchange assembly are usually arrangedadjacent to the front assembly refrigerant channels wherein therefrigerant is in the superheated state. Further in this case, it isalso usually desirable to use at least seventeen refrigerant channelsfor each of the front and rear assemblies from the viewpoint of reducingthe pressure loss of the refrigerant.

[0024] With the evaporator of the invention, the refrigerant inlet maybe provided at one end of the lower header of the rear heat exchangeassembly, and the rear heat exchange assembly may have the group ofupward refrigerant channels as each of the first and the third groups ascounted from the refrigerant inlet side, and a group of downwardrefrigerant channels as the second group as counted from the inlet side.

[0025] In this case, at least some of the upward refrigerant channels inthe first group of the rear heat exchange assembly are usually arrangedadjacent to the front assembly refrigerant channels wherein therefrigerant is in the superheated state. Further in this case, it isusually desirable to use at least thirteen refrigerant channels for eachof the front and rear assemblies from the viewpoint of reducing thepressure loss of the refrigerant.

[0026] With the evaporator of the invention, the rear heat exchangeassembly has the group of upward refrigerant channels and a group ofdownward refrigerant channels each comprising four to eight refrigerantchannels.

[0027] When the number of refrigerant channels of each channel group ofthe rear heat exchange assembly is less than four, an excessively greatrefrigerant pressure loss will result, possibly causing trouble to theflow of refrigerant. If the number of refrigerant channels of each rearassembly channel group is in excess of eight, on the other hand, theevaporator will have too great a lateral width, presenting difficulty inincorporating the evaporator into a cooling unit.

[0028] The upper and lower headers and the refrigerant channels of thefront and rear heat exchange assemblies of the evaporator of theinvention may be formed by a multiplicity of pairs of plates, each ofthe plates being provided in each of a front and a rear portion of onesurface thereof with a pair of upper and lower header recesses and achannel recess communicating at upper and lower ends thereof with theheader recesses, each pair of plates being joined to each other with therecessed surfaces thereof opposed to each other, the pairs of platesbeing fitted into juxtaposed layers with bottom walls of thecorresponding recesses joined to one another, a refrigerant passing holebeing formed in the bottom wall of the header recess disposed at eachposition where the refrigerant is to be passed, the partitions beingprovided by the respective bottom walls of upper and lower headerrecesses having no refrigerant passing hole.

[0029] With evaporator of the invention, the upper and lower headers ofthe front and rear heat exchange assemblies may be provided by front andrear two tank chambers in a pair of upper and lower tanks, and therefrigerant channels of the front and rear heat exchange assemblies maybe provided by front and rear two rows of many refrigerant tubesconnected at upper and lower ends thereof to the respective front andrear tank chambers of the upper and lower tanks, the partitions beingformed by respective walls so provided as to divide the rear tankchambers of upper and lower tanks into portions arranged laterally.

[0030] The present invention includes a vehicle provided with arefrigeration cycle having a compressor, a condenser and an evaporator,the evaporator being the evaporator of the invention described above.

[0031] Even when the clutch mechanism of the compressor of therefrigeration cycle of a motor vehicle air conditioner or the like isdisengaged, the air passing through the left and right halves of theevaporator is maintained at a uniform temperature, enabling the airvents of the vehicle to force out air of uniform temperature into theinterior thereof without the likelihood of causing discomfort to theriders.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is an overall perspective view showing a first embodimentof the invention, i.e., an evaporator for motor vehicle airconditioners.

[0033]FIG. 2 is a diagram showing the flow of refrigerant through theevaporator of FIG. 1.

[0034]FIG. 3 is a perspective view of a pair of common plates among thecomponents of the evaporator of FIG. 1.

[0035]FIG. 4 is a perspective view showing a pair of plates which areincluded among the components of the evaporator of FIG. 1 and arrangedat a position corresponding to a vertical partition in a header.

[0036]FIG. 5 is a perspective view showing a pair of plates which areincluded among the components of the evaporator of FIG. 1 and arrangedat a position corresponding to a communication tube portion.

[0037]FIG. 6 is a perspective view showing an outer plate at theevaporator left end, left end plate, outer fin and refrigerant pipeconnector attaching plate which are included among the components of theevaporator of FIG. 1.

[0038]FIG. 7 is a diagram of a second embodiment of the invention toshow the flow of refrigerant through the evaporator.

[0039]FIG. 8 is a perspective view showing a pair of plates which areincluded among the components of the evaporator according to the secondembodiment and arranged at a position corresponding to a communicationtube portion and flow-dividing communication tube portion.

[0040]FIG. 9 is a perspective view of a third embodiment of theinvention to show a pair of plates which are arranged at a positioncorresponding to a communication tube portion and flow-dividingcommunication tube portion.

[0041]FIG. 10 is an overall perspective view showing a fourth embodimentof the invention, i.e., an evaporator for motor vehicle airconditioners.

[0042]FIG. 11 is a fragmentary enlarged view in horizontal section takenalong the line XI-XI in FIG. 10 and showing the evaporator.

[0043]FIG. 12 is a diagram showing the flow of refrigerant through theevaporator of FIG. 10.

[0044]FIG. 13 is a diagram showing the flow of refrigerant through aconventional evaporator.

BEST MODE OF CARRYING OUT THE INVENTION

[0045] FIGS. 1 to 6 show a first embodiment of the invention. Withreference to FIGS. 1 and 2, an evaporator 1 according to the inventionfor use in motor vehicle air conditioners has a front heat exchangeassembly 1A and a rear heat exchange assembly 1B which are arranged atan air inlet side and an air outlet side, respectively, and adjacent toeach other. Each of the heat exchange assemblies 1A, 1B comprises a pairof upper and lower headers 2 extending laterally, and seventeen verticalrefrigerant channels 3 arranged laterally at a spacing and each havingan upper end connected to the upper header 2 and a lower end connectedto the lower header 2. A refrigerant inlet 4 is provided at the left endof the upper header 2 of the rear heat exchange assembly 1B, and arefrigerant outlet 5 is provided at the left end of the upper header 2of the front heat exchange assembly 1A. The upper headers 2 of the frontand rear heat exchange assemblies 1A, 1B communicate with each other atportions thereof toward the respective right ends through communicationtube portions 6 (communication means).

[0046] The upper and lower headers 2 of the rear heat exchange assembly1B are internally provided with vertical partitions 21 for internallydividing the headers 2 into portions in the lateral direction so as toreverse the direction of upward or rearward flow of the refrigerantthrough the refrigerant channels of the rear heat exchange assembly 1Bfor every four refrigerant channels and thereby provide a group ofupward refrigerant channels 3U in each of the left half and right halfof the rear heat exchange assembly 1B. Thus, the rear heat exchangeassembly 1B has the upward refrigerant channel group 3U as each of thesecond and fourth groups as counted from the refrigerant inlet side 4,and a downward refrigerant channel group 3D as each of the first andthird groups as counted from the inlet side 4. The upward refrigerantchannel group 3U comprises four or five refrigerant channels 3, and thedownward refrigerant channel group 3D comprises four refrigerantchannels 3.

[0047] Further the upper header 2 of the front heat exchange assembly 1Ais internally provided with a vertical partition 21 for internallydividing the header 2 into left and right two portions so that therefrigerant flows downward through the eight refrigerant channels 3 onthe right side of the assembly 1A and flows upward through the remainingnine refrigerant channels 3.

[0048] As shown in FIG. 1, each pair of the refrigerant channels 3,adjacent to each other in the lateral direction, of each of the frontand rear heat exchange assemblies 1A, 1B have therebetween a spaceserving as an air passageway 7, which has an outer fin 8.

[0049] As shown in FIGS. 1 and 3 to 6, the upper and lower headers 2 andthe refrigerant channels 3 of the front and rear heat exchangeassemblies 1A, 1B are formed by a multiplicity of pairs of plates 100.Each of the plates 100 is provided, in each of a front and a rearportion of one surface thereof, with a pair of upper and lower headerrecesses 102 and a channel recess 103 communicating at upper and lowerends thereof with the header recesses 102. Each pair of plates 100 arejoined to each other with the recessed surfaces having the recesses 102,103 thereof opposed to each other. The pairs of plates 100 are fittedinto juxtaposed layers with bottom walls 102A of the recesses 102 joinedto one another. A refrigerant passing hole 104 is formed in the bottomwall 102A of the header recess 102 disposed at each position where therefrigerant is to be passed. The partitions 21 in the upper and lowerheaders 2 of the rear heat exchange assembly 1B are provided by therespective bottom walls 102A of upper and lower header recesses 102having no refrigerant passing hole. The partition 21 in the upper header2 of the front heat exchange assembly 1A is provided by the bottom wall102A of upper header recess 102 having no refrigerant passing hole. Theplate 100 is prepared usually from an aluminum or aluminum alloy plateclad with a brazing material over opposite surfaces thereof. The pair ofplates 100 are joined to each other usually by brazing. The outer fin 8is interposed between each pair of adjacent plates 100 at anintermediate portion of their length and joined to the outer surfaces ofthe two plates 100. An end plate 110 is joined to the outer side of eachof the plates 100 positioned at left and right ends, with the outer fin8 interposed therebetween. Usually the end plate 110 is prepared alsofrom an aluminum or aluminum alloy plate clad with a brazing materialover one or each of opposite surfaces thereof, and is joined to theouter surface of the plate 100 at the end by brazing.

[0050]FIG. 3 shows a pair of common plates 100. These plates 100 eachhave a refrigerant passing hole 104 in the bottom wall 102A of each ofupper and lower header recesses 102 in each of the front and rearportions of the plate. A corrugated inner fin 9 is provided in each offront and rear two refrigerant channels 3 formed by front and rearchannel recesses 103 of the two plates 100. The inner fin 9 is madeusually from a corrugated sheet of aluminum or aluminum alloy and joinedto the inner surfaces of the two plates 100 by brazing.

[0051]FIG. 4 shows a pair of plates 100 to be disposed at a positioncorresponding to the vertical partition 21 of the header 2. Withreference to FIG. 4, of the four header recesses 102 of one of theplates 100, the upper header recess 102 on the rear side has norefrigerant passing hole in the bottom wall 102A thereof, and thisbottom wall 102A provides the vertical partition 21 in the upper header2 of the rear heat exchange assembly 1B. The other vertical partitions21 are formed in the same manner as described above.

[0052]FIG. 5 shows a pair of plates 100 to be disposed at a positioncorresponding to the communication tube portion 6. With reference toFIG. 5, one of the plates 100 is provided in the inner surface thereofwith a tube recess 106 extending from front to rear to cause the frontand rear two upper header recesses 102 to communicate with each other.The tube recess 106 of this plate 100 and an inner surface portion ofthe other plate 100 opposed thereto form the communication tube portion6. Incidentally, the other plate 100 may also have the same tube recessas above to provide a communication tube portion by the tube recesses ofthe two plates 100.

[0053] According to the present embodiment, the communication tubeportions 6 which are five in total number are provided in correspondingrelation to the five refrigerant channels 3 of the upward refrigerantchannel group 3U at the right of the rear heat exchange assembly 1B,whereas a reduced number of tube portions 6 may be used insofar as theresulting refrigerant pressure loss poses no problem. Further thecommunication tube portions 6 each provided by the recess 106 in thepair of plates 100 serve to hold the upper headers 2 of the front andrear heat exchange assemblies 1A, 1B in communication with each other inthe case of the present embodiment. However, alternatively usable is acommunication tube portion formed in an end plate for causing the rightends of the upper headers 2 to communicate with each other. The endplate having such a tube portion can be formed by preparing a pair ofplates each provided in one surface thereof with a tube recess extendingforward or rearward at an upper end portion thereof and joining theplates with the recesses facing toward each other. Further according tothe present embodiment, the upper headers 2 of the front and rear heatexchange assemblies 1A. 1B are held in communication with each other bythe tube portions 6 at the header portions toward the right endsthereof. Depending on the refrigerant flow pattern, however, therearises a need to provide communication means for holding the upperheader 2 of the rear assembly 1B and the lower header 2 of the frontassembly 1A in communication with each other at their right ends, or forcausing the lower header 2 of the rear assembly 1B to communicate withthe upper header 2 of the front assembly 1A at their right ends. Usablein such a case is an end plate which has a communication tube portionextending obliquely therein to hold the header right ends incommunication with each other. The end plate can be formed by preparinga pair of plates each provided in one surface thereof with an obliquelyextending tube recess and joining the plates with the recesses facingtoward each other.

[0054]FIG. 6 shows an outer plate 100 at the evaporator left end, leftend plate 110, outer fin 8 and refrigerant pipe connector attachingplate 10. With reference to FIG. 6, the plate 100 is the same as theplate 100 shown in FIG. 3. The bottom wall 102A of the rear upper headerrecess 102 has a refrigerant passing hole 104 serving as the refrigerantinlet 4, and the bottom wall 102A of the front upper header recess 102has a refrigerant passing hole 104 serving as the refrigerant outlet 5.The end plate 110 is provided in its outer surface with recesses 112similar to and corresponding to the four header recesses 102 of theplate 100. The upper front and rear two recesses 112 of the end plate110 have respective bottom walls 112A, in which holes 114 are formed soas to be in register with the refrigerant inlet 4 and the refrigerantoutlet 5. On the other hand, the bottom walls 112A of the lower frontand rear two recesses 112 of the end plate 110 have no hole to serve asthe left end walls of the lower headers 2 of the front and rear heatexchange assemblies 1A, 1B. The outer fin 8 is prepared usually from acorrugated sheet of aluminum or aluminum alloy and joined to the opposedsurfaces of the plate 100 and the end plate 110 by brazing. Therefrigerant pipe connector attaching plate 10 is made usually from analuminum or aluminum alloy plate and joined to the upper end portion ofthe end plate 110 by brazing. The plate 10 has front and rear two holes10A communicating with the respective holes 114 in the front and reartwo recess bottom walls 112A of the end plate 110 and is provided on theouter surface thereof with an unillustrated refrigerant pipe connectorjoined thereto as by welding. An outer plate 100 at the evaporator rightend, right end plate 110, and outer fin 8 to be interposed between theseplates are substantially the same as the plate 100, end plate 110 andouter fin 8 shown in FIG. 6, respectively.

[0055] In the case where the switch for the motor vehicle airconditioner is closed, with the clutch mechanism of the compressor iscoupled to the crankshaft of the engine, the refrigerant flows throughthe evaporator 1 as shown in FIG. 2. Stated more specifically, therefrigerant introduced into the evaporator 1 via the inlet 4 flowsthrough the rear heat exchange assembly 1B via the upper and lowerheaders 2 of the assembly 1B, i.e., through the downward refrigerantchannel group 3D at the left, the upward refrigerant channel group 3U atthe left, the downward refrigerant channel group 3D at the right, andthe upward refrigerant channel group 3U at the right in this order, thenflows through the communication tube portions 6 to the front heatexchange assembly 1A, thereafter flows through the downward refrigerantchannel group 3D at the right of the front assembly 1A and the upwardrefrigerant channel group 3U at the left thereof via the upper and lowerheaders 2 of the assembly 1A, and is discharged from the outlet 5. Inthis flow pattern, the refrigerant flowing through the refrigerantchannel group has a lower temperature when the group is in the rearassembly 1B and closer to the refrigerant inlet 4 and a highertemperature when the group is in the front assembly 1A and closer to therefrigerant outlet 5, with the result that the portions of air A passingthrough the left and right halves of the evaporator 1 are generallyuniform in temperature. With the present embodiment, the portionswherein the refrigerant is in a superheated, i.e., so-called superheatedportions 30, are usually several refrigerant channels 3 positioned atthe right and included the nine refrigerant channels 3 of the upwardrefrigerant channel group 3U at the left side of the front heat exchangeassembly 1A. The rear heat exchange assembly 1B has an upwardrefrigerant channel group 3U positioned at the left side thereof incorresponding relation with these superheated portions 30.

[0056] On the other hand, when the clutch mechanism of the compressor isautomatically disengaged to prevent overcooling of air, with the switchfor the motor vehicle air conditioner closed, air A is continued to passthrough the evaporator 1, but the supply of the refrigerant to theevaporator 1 is temporarily interrupted. In the case where the flow ofrefrigerant through the conventional evaporator 500 shown in FIG. 13 isthus halted, a portion of refrigerant having a relatively lowtemperature stagnates in a large amount in the upward refrigerantchannel group 503U arranged in the right half of the rear heat exchangeassembly 500B of the evaporator 500, while the refrigerant does notstagnates in such a large amount in the downward refrigerant channelgroup 503D in the left half of the assembly, consequently producing atemperature difference between the air portions passing through therespective left and right halves of the evaporator 500. In the case ofthe evaporator 1 shown in FIG. 2, the refrigerant stagnates in largeamounts in the upward refrigerant channel groups 3U at the respectiveleft and right sides of the rear heat exchange assembly 1B, such thatalmost no temperature difference occurs between the left half and theright half of the rear assembly 1B. Moreover, the upward refrigerantchannel group 3U at the left side of the assembly 1B is juxtaposed withthe superheated portions 30 of the front assembly 1A across thedirection of flow of air. As a result, the portions of air passingthrough the left and right halves respectively become substantiallyuniform in temperature.

[0057]FIGS. 7 and 8 show a second embodiment of the invention. Thisembodiment is the same as the first embodiment with the exception of thefollowing. First as shown in FIG. 7, front and rear heat exchangeassemblies 1A, 1B each have twenty-one vertical refrigerant channels 3.The rear heat exchange assembly 1B has a downward refrigerant channelgroup 3D at the left, upward refrigerant channel group 3U at the left,downward refrigerant channel group 3D at the right and upwardrefrigerant channel group 3U at the right which comprise five, six, sixand four refrigerant channels 3, respectively.

[0058] The refrigerant to be caused to flow into the group of upwardrefrigerant channel group 3U in the right side of the rear heat exchangeassembly 1B is made to dividedly flow into and flow upward through fourrefrigerant channels 3 of the front heat exchange assembly 1A which areadjacent to the four refrigerant channels 3 of the rear heat exchangeassembly 1B constituting the group 3U, by causing the lower headers 2 ofthe front and rear heat exchange assemblies 1A, 1B to communicate witheach other by flow-dividing communication tube portions 11(flow-dividing communication means) at the header portions correspondingto the plurality of refrigerant channels 3. This reduces the pressureloss of the refrigerant.

[0059] The upper and lower headers 2 of the front heat exchange assembly1A are each internally divided into left and right two portions by avertical partition 21 so that the refrigerant flows upward through thefour channels 3 at the right, downward through the subsequent eightrefrigerant channels 3 and upward through the remaining nine refrigerantchannels 3.

[0060]FIG. 8 shows the pair of plates 100 to be arranged at thepositions corresponding to the communication tube portions 6 andflow-dividing communication tube portions 11. With reference to FIG. 8,one of the plates 100 is provided in the inner surface thereof with atube recess 106 extending from front to rear to cause the front and reartwo upper header recesses 102 to communicate with each other. The tuberecess 106 of this plate 100 and an inner surface portion of the otherplate 100 opposed thereto form the communication tube portion 6. Theother plate 100 is provided in the inner surface thereof with aflow-dividing tube recess 111 extending from front to rear to cause thefront and rear two lower header recesses 102 to communicate with eachother. The flow-dividing tube recess 111 of the other plate 100 and aninner surface portion of the above-mentioned one plate 100 opposedthereto form the flow-dividing communication tube portion 11.

[0061]FIG. 9 shows a third embodiment of the invention. This embodimentis the same as the second embodiment with the exception of thefollowing. FIG. 9 shows a pair of plates 100 corresponding to thoseshown in FIG. 8 which shows the second embodiment, i.e., a pair ofplates 100 to be positioned in corresponding relation with thecommunication tube portions 6 and flow-dividing communication tubeportions 11. The front and rear two channel recesses 103 of each plate100 of the pair are joined so as to communicate with each other over theentire length thereof. In other words, each of the pair of plates 100 isprovided in its inner surface with a large channel recess 103A having awidth approximate to the width of the plate 100 and serving as the frontand rear two channel recesses. With the evaporator of this embodiment,the four refrigerant channels 3 of the rear heat exchange assembly 1Bwhich provide an upward refrigerant channel group 3U at the right areeach joined to the corresponding one of the four refrigerant channels 3of the front heat exchange assembly 1A adjacent to these channels 3 tohold communication therebetween (see FIGS. 1 and 2). This constructionfurther reduces the pressure loss of the refrigerant. The tube recess106 and the flow-dividing tube recess 111 are formed in each of theplates 100. The inner fin 9 to be used has a width corresponding to thewidth of the recess 103A.

[0062] FIGS. 10 to 12 show a fourth embodiment of the invention. Thisembodiment is the same as the first embodiment with the exception of thefollowing. With this embodiment, i.e., with an evaporator 1X, upper andlower headers 2 of front and rear heat exchange assemblies 1A, 1B areprovided by front and rear two tank chambers 121 in a pair of upper andlower tanks 12 as shown in FIGS. 10 and 11. The front and rear heatexchange assemblies 1A, 1B have refrigerant channels 3 provided by frontand rear two rows of many refrigerant vertical tubes 13 connected at theupper and lower ends thereof to the respective front and rear tankchambers 121 of the upper and lower tanks 12. The upper and lowerheaders 2 of the rear heat exchange assembly 1B have vertical partitions21 provided by vertical walls 122 which are so arranged as to divide therear tank chambers 121 of upper and lower tanks 12 into left and rightportions. The upper header 2 of the front heat exchange assembly 1A hasa vertical partition 21 provided by a vertical wall 122 which is sodisposed as to divide the front tank chamber 121 of the upper tank 12into left and right portions.

[0063] An outer fin 8 is interposed between each pair of laterallyadjacent vertical tubes 13 and joined to the outer surfaces thereof. Thetanks 12, vertical tubes 13 and outer fins 8 are all made of aluminum oraluminum alloy. These components are joined to one another usually bybrazing.

[0064] The vertical tube 13 is flat and has a lateral width smaller thanthe front-to-rear width thereof. As shown in FIG. 11, the tube 13 hasleft and right walls 131 each having a planar outer surface, and aplurality of reinforcing walls 132 interconnecting the walls 131 andarranged forward or rearward as spaced apart from one another. Aplurality of refrigerant passageways 133 arranged forward or rearward inparallel are formed in the interior of the vertical tube 13.

[0065] With reference to FIG. 10, the upper and lower tanks 12 are eachdivided into front and rear two tank chambers 121 by a verticalpartition wall 120 extending leftward or rightward, i.e., laterally. Thepartition wall 120 of the upper tank 12 has a communication hole 123(communication means) formed in a right end portion thereof for holdingthe front and rear tank chambers 121 in communication with each other attheir right ends.

[0066]FIG. 12 shows the flow of refrigerant through the evaporator 1Xdescribed. The flow pattern is the same as that shown in FIG. 2. Statedmore specifically, the refrigerant introduced into the evaporator 1X viathe inlet 4 flows through the rear heat exchange assembly 1B via theupper and lower headers 2 of the assembly 1B, i.e., through the downwardrefrigerant channel group 3D at the left, the upward refrigerant channelgroup 3U at the left, the downward refrigerant channel group 3D at theright, and the upward refrigerant channel group 3U at the right in thisorder, then flows through the communication hole 123 into the front heatexchange assembly 1A, thereafter flows through the downward refrigerantchannel group 3D at the right of the front assembly 1A and the upwardrefrigerant channel group 3U at the left thereof via the upper and lowerheaders 2 of the assembly 1A, and is discharged from the outlet 5.

[0067] Embodiments have been described above for illustrative purposeonly. The present invention can of course be practiced as suitablymodified without departing from the scope of the invention as set forthin the appended claims.

1. An evaporator comprising: a front heat exchange assembly and a rearheat exchange assembly arranged at an air inlet side and an air outletside, respectively, and adjacent to each other, each of the heatexchange assemblies comprising a pair of upper and lower headersextending laterally, and a multiplicity of refrigerant channels arrangedlaterally at a spacing and each having an upper end connected to theupper header and a lower end connected to the lower header, arefrigerant inlet being provided at one end of the upper or lower headerof the rear heat exchange assembly, a refrigerant outlet being providedat one end of the upper or lower header of the front heat exchangeassembly, the upper or lower header of the rear heat exchange assemblycommunicating at a portion thereof toward the other end with the upperor lower header of the front heat exchange assembly at a portion thereoftoward the other end by communication means, the upper and lower headersof the rear heat exchange assembly being internally provided withvertical partitions for internally dividing the headers into portionsarranged laterally so as to reverse the direction of upward or rearwardflow of a refrigerant through the refrigerant channels of the rear heatexchange assembly for every specified number of refrigerant channels andthereby provide at least one group of upward refrigerant channels ineach of a left half and a right half of the rear heat exchange assembly.2. An evaporator according to claim 1 wherein the refrigerant channelsof the rear heat exchange assembly adjacent to the refrigerant channelsof the front heat exchange assembly wherein the refrigerant is in ansuperheated state are included in the group of upward refrigerantchannels.
 3. An evaporator according to claim 1 wherein the refrigerantto be caused to flow into the group of upward refrigerant channels ofthe rear heat exchange assembly which are positioned remotest from therefrigerant inlet is made to dividedly flow into and flow upward througha plurality of refrigerant channels of the front heat exchange assemblywhich are adjacent to the plurality of refrigerant channels of the rearheat exchange assembly constituting the group, by causing the lowerheaders of the front and rear heat exchange assemblies to communicatewith each other by flow-dividing communication means at the headerportions corresponding to the plurality of refrigerant channels.
 4. Anevaporator according to claim 1 wherein the refrigerant to be caused toflow into the group of downward refrigerant channels of the rear heatexchange assembly which are positioned remotest from the refrigerantinlet is made to dividedly flow into and downward through a plurality ofrefrigerant channels of the front heat exchange assembly which areadjacent to the plurality of refrigerant channels of the rear heatexchange assembly constituting the group, by causing the upper headersof the front and rear heat exchange assemblies to communicate with eachother through flow-dividing communication means at the header portionscorresponding to the plurality of refrigerant channels.
 5. An evaporatoraccording to claim 1 wherein the refrigerant inlet is provided at oneend of the lower header of the rear heat exchange assembly, and the rearheat exchange assembly has the group of upward refrigerant channels aseach of the first and the third groups as counted from the refrigerantinlet side, and a group of downward refrigerant channels as each of thesecond and fourth groups as counted from the inlet side.
 6. Anevaporator according to claim 1 wherein the refrigerant inlet isprovided at one end of the upper header of the rear heat exchangeassembly, and the rear heat exchange assembly has the group of upwardrefrigerant channels as each of the second and the fourth groups ascounted from the refrigerant inlet side, and a group of downwardrefrigerant channels as each of the first and third groups as countedfrom the inlet side.
 7. An evaporator according to claim 1 wherein therefrigerant inlet is provided at one end of the lower header of the rearheat exchange assembly, and the rear heat exchange assembly has thegroup of upward refrigerant channels as each of the first and the thirdgroups as counted from the refrigerant inlet side, and a group ofdownward refrigerant channels as the second group as counted from theinlet side.
 8. An evaporator according to claim 1 wherein the rear heatexchange assembly has the group of upward refrigerant channels and agroup of downward refrigerant channels each comprising four to eightrefrigerant channels.
 9. An evaporator according to claim 1 wherein theupper and lower headers and the refrigerant channels of the front andrear heat exchange assemblies are formed by a multiplicity of pairs ofplates, each of the plates being provided in each of a front and a rearportion of one surface thereof with a pair of upper and lower headerrecesses and a channel recess communicating at upper and lower endsthereof with the header recesses, each pair of plates being joined toeach other with the recessed surfaces thereof opposed to each other, thepairs of plates being fitted into juxtaposed layers with bottom walls ofthe corresponding recesses joined to one another, a refrigerant passinghole being formed in the bottom wall of the header recess disposed ateach position where the refrigerant is to be passed, the partitionsbeing provided by the respective bottom walls of upper and lower headerrecesses having no refrigerant passing hole.
 10. An evaporator accordingto claim 1 wherein the upper and lower headers of the front and rearheat exchange assemblies are provided by front and rear two tankchambers in a pair of upper and lower tanks, and the refrigerantchannels of the front and rear heat exchange assemblies are provided byfront and rear two rows of many refrigerant tubes connected at upper andlower ends thereof to the respective front and rear tank chambers of theupper and lower tanks, the partitions being formed by respective wallsso provided as to divide the rear tank chambers of upper and lower tanksinto portions arranged laterally.
 11. A vehicle provided with arefrigeration cycle having a compressor, a condenser and an evaporator,the evaporator being an evaporator according to claim
 1. 12. A vehicleprovided with a refrigeration cycle having a compressor, a condenser andan evaporator, the evaporator being an evaporator according to claim 2.13. A vehicle provided with a refrigeration cycle having a compressor, acondenser and an evaporator, the evaporator being an evaporatoraccording to claim
 3. 14. A vehicle provided with a refrigeration cyclehaving a compressor, a condenser and an evaporator, the evaporator beingan evaporator according to claim
 4. 15. A vehicle provided with arefrigeration cycle having a compressor, a condenser and an evaporator,the evaporator being an evaporator according to claim
 5. 16. A vehicleprovided with a refrigeration cycle having a compressor, a condenser andan evaporator, the evaporator being an evaporator according to claim 6.17. A vehicle provided with a refrigeration cycle having a compressor, acondenser and an evaporator, the evaporator being an evaporatoraccording to claim
 7. 18. A vehicle provided with a refrigeration cyclehaving a compressor, a condenser and an evaporator, the evaporator beingan evaporator according to claim
 8. 19. A vehicle provided with arefrigeration cycle having a compressor, a condenser and an evaporator,the evaporator being an evaporator according to claim
 9. 20. A vehicleprovided with a refrigeration cycle having a compressor, a condenser andan evaporator, the evaporator being an evaporator according to claim 10.